// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: http://codemirror.net/LICENSE

// Because sometimes you need to style the cursor's line.
//
// Adds an option 'styleActiveLine' which, when enabled, gives the
// active line's wrapping <div> the CSS class "CodeMirror-activeline",
// and gives its background <div> the class "CodeMirror-activeline-background".

(function(mod) {
	if (typeof exports == "object" && typeof module == "object") // CommonJS
		mod(require("../../lib/codemirror"));
	else if (typeof define == "function" && define.amd) // AMD
		define(["../../lib/codemirror"], mod);
	else // Plain browser env
		mod(CodeMirror);
})(function(CodeMirror) {
	"use strict";
	var WRAP_CLASS = "CodeMirror-activeline";
	var BACK_CLASS = "CodeMirror-activeline-background";

	CodeMirror.defineOption("styleActiveLine", false, function(cm, val, old) {
		var prev = old && old != CodeMirror.Init;
		if (val && !prev) {
			cm.state.activeLines = [];
			updateActiveLines(cm, cm.listSelections());
			cm.on("beforeSelectionChange", selectionChange);
		} else if (!val && prev) {
			cm.off("beforeSelectionChange", selectionChange);
			clearActiveLines(cm);
			delete cm.state.activeLines;
		}
	});

	function clearActiveLines(cm) {
		for (var i = 0; i < cm.state.activeLines.length; i++) {
			cm.removeLineClass(cm.state.activeLines[i], "wrap", WRAP_CLASS);
			cm.removeLineClass(cm.state.activeLines[i], "background", BACK_CLASS);
		}
	}

	function sameArray(a, b) {
		if (a.length != b.length) return false;
		for (var i = 0; i < a.length; i++)
			if (a[i] != b[i]) return false;
		return true;
	}

	function updateActiveLines(cm, ranges) {
		var active = [];
		for (var i = 0; i < ranges.length; i++) {
			var range = ranges[i];
			if (!range.empty()) continue;
			var line = cm.getLineHandleVisualStart(range.head.line);
			if (active[active.length - 1] != line) active.push(line);
		}
		if (sameArray(cm.state.activeLines, active)) return;
		cm.operation(function() {
			clearActiveLines(cm);
			for (var i = 0; i < active.length; i++) {
				cm.addLineClass(active[i], "wrap", WRAP_CLASS);
				cm.addLineClass(active[i], "background", BACK_CLASS);
			}
			cm.state.activeLines = active;
		});
	}

	function selectionChange(cm, sel) {
		updateActiveLines(cm, sel.ranges);
	}
});
